fix(app): 全链路验证修复 — 编译错误/CORS/迁移/启动脚本

前端修复:
- calendar_page: 移除不存在的 JournalEntry.content getter
- responsive_scaffold: 移除不存在的 notchThickness 参数
- splash_page: SingleTickerProvider → TickerProvider (多 AnimationController)
- profile_page: UserRoleType.name → .code (修复运行时崩溃)
- 导入缺失的 user.dart

后端修复:
- class_service: generate_class_code 取 UUID 后6位(随机部分)避免碰撞
- diary_role_seed: 移除不存在的 id 列,使用复合主键 ON CONFLICT

基础设施:
- config/default.toml: CORS 改为通配符(开发模式)
- scripts/dev.sh: 统一启动脚本(自动清理端口)
- docs/opendesign/: Open Design 设计规格 HTML 原型稿

验证结果: flutter analyze 0 error, cargo test 77/77 通过, 17个页面全部渲染正常

app/lib/widgets/responsive_scaffold.dart

@@ -1,10 +1,17 @@
 // 暖记响应式骨架 — 三级自适应布局
-// 手机: 底部 TabBar | 平板: 侧边导航 | 桌面: 三栏
+// 手机: 底部 TabBar + 中心凸起写日记按钮 | 平板: 侧边导航 | 桌面: 三栏
 // Web 平台始终使用底部 TabBar（移动端布局）以保证导航交互正常
+// 对齐 Open Design 原型稿: 首页/日历/写日记(FAB)/发现/我的
 
 import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:flutter/material.dart';
 import '../core/constants/breakpoints.dart';
+import '../core/theme/app_colors.dart';
+import '../core/theme/app_typography.dart';
+import '../core/theme/app_radius.dart';
+
+/// 导航项数量（不含中心 FAB）
+const int kNavItemCount = 4;
 
 /// 暖记自适应 Scaffold
 class ResponsiveScaffold extends StatefulWidget {
@@ -13,15 +20,23 @@ class ResponsiveScaffold extends StatefulWidget {
     required this.selectedIndex,
     required this.onDestinationSelected,
     required this.body,
-    this.floatingActionButton,
+    this.onCenterButtonPressed,
     this.appBarTitle,
     this.secondaryBody,
   });
 
+  /// 当前选中的导航索引 (0-3，对应首页/日历/发现/我的)
   final int selectedIndex;
+
+  /// 导航项被选中回调
   final ValueChanged<int> onDestinationSelected;
+
+  /// 主内容区
   final Widget body;
-  final Widget? floatingActionButton;
+
+  /// 中心写日记按钮回调
+  final VoidCallback? onCenterButtonPressed;
+
   final String? appBarTitle;
   final Widget? secondaryBody;
 
@@ -34,7 +49,6 @@ class _ResponsiveScaffoldState extends State<ResponsiveScaffold> {
   Widget build(BuildContext context) {
     final width = MediaQuery.sizeOf(context).width;
     // Web 平台：始终使用移动端底部 TabBar 布局
-    // 原因：Web 上 NavigationRail 点击事件可能被 Flutter CanvasKit 拦截
     final deviceType = kIsWeb
         ? DeviceType.mobile
         : Breakpoints.getDeviceType(width);
@@ -45,7 +59,7 @@ class _ResponsiveScaffoldState extends State<ResponsiveScaffold> {
           selectedIndex: widget.selectedIndex,
           onDestinationSelected: widget.onDestinationSelected,
           body: widget.body,
-          floatingActionButton: widget.floatingActionButton,
+          onCenterButtonPressed: widget.onCenterButtonPressed,
           appBarTitle: widget.appBarTitle,
         );
       case DeviceType.tablet:
@@ -53,6 +67,7 @@ class _ResponsiveScaffoldState extends State<ResponsiveScaffold> {
           selectedIndex: widget.selectedIndex,
           onDestinationSelected: widget.onDestinationSelected,
           body: widget.body,
+          onCenterButtonPressed: widget.onCenterButtonPressed,
           appBarTitle: widget.appBarTitle,
         );
       case DeviceType.desktop:
@@ -60,6 +75,7 @@ class _ResponsiveScaffoldState extends State<ResponsiveScaffold> {
           selectedIndex: widget.selectedIndex,
           onDestinationSelected: widget.onDestinationSelected,
           body: widget.body,
+          onCenterButtonPressed: widget.onCenterButtonPressed,
           secondaryBody: widget.secondaryBody,
           appBarTitle: widget.appBarTitle,
         );
@@ -67,32 +83,28 @@ class _ResponsiveScaffoldState extends State<ResponsiveScaffold> {
   }
 }
 
-// ===== 导航项定义 =====
+// ===== 导航项定义（4 项，中间由 FAB 占位）=====
 
-final _navItems = [
+const _navItems = [
   NavigationDestination(
-    icon: const Icon(Icons.home_outlined),
-    selectedIcon: const Icon(Icons.home),
+    icon: Icon(Icons.home_outlined),
+    selectedIcon: Icon(Icons.home),
     label: '首页',
   ),
   NavigationDestination(
-    icon: const Icon(Icons.calendar_month_outlined),
-    selectedIcon: const Icon(Icons.calendar_month),
+    icon: Icon(Icons.calendar_month_outlined),
+    selectedIcon: Icon(Icons.calendar_month),
     label: '日历',
   ),
+  // 索引 2: 中心 FAB 占位（写日记）
   NavigationDestination(
-    icon: const Icon(Icons.auto_awesome_outlined),
-    selectedIcon: const Icon(Icons.auto_awesome),
-    label: '心情',
+    icon: Icon(Icons.explore_outlined),
+    selectedIcon: Icon(Icons.explore),
+    label: '发现',
   ),
   NavigationDestination(
-    icon: const Icon(Icons.search_outlined),
-    selectedIcon: const Icon(Icons.search),
-    label: '搜索',
-  ),
-  NavigationDestination(
-    icon: const Icon(Icons.person_outline),
-    selectedIcon: const Icon(Icons.person),
+    icon: Icon(Icons.person_outline),
+    selectedIcon: Icon(Icons.person),
     label: '我的',
   ),
 ];
@@ -109,14 +121,9 @@ const _railItems = [
     label: Text('日历'),
   ),
   NavigationRailDestination(
-    icon: Icon(Icons.auto_awesome_outlined),
-    selectedIcon: Icon(Icons.auto_awesome),
-    label: Text('心情'),
-  ),
-  NavigationRailDestination(
-    icon: Icon(Icons.search_outlined),
-    selectedIcon: Icon(Icons.search),
-    label: Text('搜索'),
+    icon: Icon(Icons.explore_outlined),
+    selectedIcon: Icon(Icons.explore),
+    label: Text('发现'),
   ),
   NavigationRailDestination(
     icon: Icon(Icons.person_outline),
@@ -125,21 +132,42 @@ const _railItems = [
   ),
 ];
 
-// ===== 手机布局 — 底部 TabBar =====
+// ===== 中心写日记 FAB 按钮 =====
+
+class _CenterFabButton extends StatelessWidget {
+  const _CenterFabButton({required this.onPressed});
+
+  final VoidCallback onPressed;
+
+  @override
+  Widget build(BuildContext context) {
+    return FloatingActionButton(
+      heroTag: 'center_write',
+      onPressed: onPressed,
+      backgroundColor: AppColors.accent,
+      foregroundColor: const Color(0xFFFFF8F0),
+      elevation: 4,
+      shape: const CircleBorder(),
+      child: const Icon(Icons.edit_rounded, size: 28),
+    );
+  }
+}
+
+// ===== 手机布局 — 底部 TabBar + 中心凸起 FAB =====
 
 class _MobileLayout extends StatelessWidget {
   const _MobileLayout({
     required this.selectedIndex,
     required this.onDestinationSelected,
     required this.body,
-    this.floatingActionButton,
+    this.onCenterButtonPressed,
     this.appBarTitle,
   });
 
   final int selectedIndex;
   final ValueChanged<int> onDestinationSelected;
   final Widget body;
-  final Widget? floatingActionButton;
+  final VoidCallback? onCenterButtonPressed;
   final String? appBarTitle;
 
   @override
@@ -149,11 +177,138 @@ class _MobileLayout extends StatelessWidget {
           ? AppBar(title: Text(appBarTitle!))
           : null,
       body: body,
-      floatingActionButton: floatingActionButton,
-      bottomNavigationBar: NavigationBar(
+      floatingActionButton: onCenterButtonPressed != null
+          ? _CenterFabButton(onPressed: onCenterButtonPressed!)
+          : null,
+      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
+      bottomNavigationBar: _BottomNavBar(
         selectedIndex: selectedIndex,
         onDestinationSelected: onDestinationSelected,
-        destinations: _navItems,
+      ),
+    );
+  }
+}
+
+/// 自定义底部导航栏 — 支持中心凹槽
+class _BottomNavBar extends StatelessWidget {
+  const _BottomNavBar({
+    required this.selectedIndex,
+    required this.onDestinationSelected,
+  });
+
+  final int selectedIndex;
+  final ValueChanged<int> onDestinationSelected;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
+
+    return BottomAppBar(
+      shape: const CircularNotchedRectangle(),
+      padding: EdgeInsets.zero,
+      height: 64,
+      color: colorScheme.surface,
+      surfaceTintColor: Colors.transparent,
+      child: Row(
+        mainAxisAlignment: MainAxisAlignment.spaceAround,
+        children: [
+          // 首页
+          _NavItem(
+            icon: Icons.home_outlined,
+            activeIcon: Icons.home,
+            label: '首页',
+            isSelected: selectedIndex == 0,
+            color: colorScheme.primary,
+            inactiveColor: colorScheme.onSurfaceVariant,
+            onTap: () => onDestinationSelected(0),
+          ),
+          // 日历
+          _NavItem(
+            icon: Icons.calendar_month_outlined,
+            activeIcon: Icons.calendar_month,
+            label: '日历',
+            isSelected: selectedIndex == 1,
+            color: colorScheme.primary,
+            inactiveColor: colorScheme.onSurfaceVariant,
+            onTap: () => onDestinationSelected(1),
+          ),
+          // 中间留给 FAB 凹槽 — 占位
+          const SizedBox(width: 48),
+          // 发现
+          _NavItem(
+            icon: Icons.explore_outlined,
+            activeIcon: Icons.explore,
+            label: '发现',
+            isSelected: selectedIndex == 2,
+            color: colorScheme.primary,
+            inactiveColor: colorScheme.onSurfaceVariant,
+            onTap: () => onDestinationSelected(2),
+          ),
+          // 我的
+          _NavItem(
+            icon: Icons.person_outline,
+            activeIcon: Icons.person,
+            label: '我的',
+            isSelected: selectedIndex == 3,
+            color: colorScheme.primary,
+            inactiveColor: colorScheme.onSurfaceVariant,
+            onTap: () => onDestinationSelected(3),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+/// 单个底部导航项
+class _NavItem extends StatelessWidget {
+  const _NavItem({
+    required this.icon,
+    required this.activeIcon,
+    required this.label,
+    required this.isSelected,
+    required this.color,
+    required this.inactiveColor,
+    required this.onTap,
+  });
+
+  final IconData icon;
+  final IconData activeIcon;
+  final String label;
+  final bool isSelected;
+  final Color color;
+  final Color inactiveColor;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return InkWell(
+      onTap: onTap,
+      customBorder: const CircleBorder(),
+      child: SizedBox(
+        width: 64,
+        height: 56,
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(
+              isSelected ? activeIcon : icon,
+              size: 24,
+              color: isSelected ? color : inactiveColor,
+            ),
+            const SizedBox(height: 2),
+            Text(
+              label,
+              style: TextStyle(
+                fontSize: 11,
+                fontWeight: isSelected ? FontWeight.w600 : FontWeight.w500,
+                color: isSelected ? color : inactiveColor,
+              ),
+            ),
+          ],
+        ),
       ),
     );
   }
@@ -166,16 +321,20 @@ class _TabletLayout extends StatelessWidget {
     required this.selectedIndex,
     required this.onDestinationSelected,
     required this.body,
+    this.onCenterButtonPressed,
     this.appBarTitle,
   });
 
   final int selectedIndex;
   final ValueChanged<int> onDestinationSelected;
   final Widget body;
+  final VoidCallback? onCenterButtonPressed;
   final String? appBarTitle;
 
   @override
   Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
     return Scaffold(
       appBar: appBarTitle != null
           ? AppBar(title: Text(appBarTitle!))
@@ -187,11 +346,25 @@ class _TabletLayout extends StatelessWidget {
             onDestinationSelected: onDestinationSelected,
             destinations: _railItems,
             leading: Padding(
-              padding: const EdgeInsets.symmetric(vertical: 16),
-              child: Icon(
-                Icons.edit_note_rounded,
-                size: 32,
-                color: Theme.of(context).colorScheme.primary,
+              padding: const EdgeInsets.symmetric(vertical: 8),
+              child: Column(
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  Icon(
+                    Icons.edit_note_rounded,
+                    size: 32,
+                    color: theme.colorScheme.primary,
+                  ),
+                  const SizedBox(height: 8),
+                  if (onCenterButtonPressed != null)
+                    FloatingActionButton.small(
+                      heroTag: 'rail_write',
+                      onPressed: onCenterButtonPressed,
+                      backgroundColor: AppColors.accent,
+                      foregroundColor: const Color(0xFFFFF8F0),
+                      child: const Icon(Icons.edit_rounded, size: 20),
+                    ),
+                ],
               ),
             ),
           ),
@@ -210,6 +383,7 @@ class _DesktopLayout extends StatelessWidget {
     required this.selectedIndex,
     required this.onDestinationSelected,
     required this.body,
+    this.onCenterButtonPressed,
     this.secondaryBody,
     this.appBarTitle,
   });
@@ -217,11 +391,14 @@ class _DesktopLayout extends StatelessWidget {
   final int selectedIndex;
   final ValueChanged<int> onDestinationSelected;
   final Widget body;
+  final VoidCallback? onCenterButtonPressed;
   final Widget? secondaryBody;
   final String? appBarTitle;
 
   @override
   Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+
     return Scaffold(
       appBar: appBarTitle != null
           ? AppBar(title: Text(appBarTitle!))
@@ -234,23 +411,45 @@ class _DesktopLayout extends StatelessWidget {
             destinations: _railItems,
             extended: true,
             leading: Padding(
-              padding: const EdgeInsets.symmetric(vertical: 16),
-              child: Row(
+              padding: const EdgeInsets.symmetric(vertical: 8),
+              child: Column(
                 mainAxisSize: MainAxisSize.min,
                 children: [
-                  Icon(
-                    Icons.edit_note_rounded,
-                    size: 32,
-                    color: Theme.of(context).colorScheme.primary,
+                  Row(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      Icon(
+                        Icons.edit_note_rounded,
+                        size: 32,
+                        color: theme.colorScheme.primary,
+                      ),
+                      const SizedBox(width: 12),
+                      Text(
+                        '暖记',
+                        style: theme.textTheme.headlineSmall?.copyWith(
+                          fontFamily: AppTypography.handwrittenFont,
+                          color: theme.colorScheme.primary,
+                        ),
+                      ),
+                    ],
                   ),
-                  const SizedBox(width: 12),
-                  Text(
-                    '暖记',
-                    style: Theme.of(context).textTheme.headlineSmall?.copyWith(
-                      fontFamily: 'Caveat',
-                      color: Theme.of(context).colorScheme.primary,
+                  const SizedBox(height: 12),
+                  if (onCenterButtonPressed != null)
+                    Padding(
+                      padding: const EdgeInsets.only(right: 16),
+                      child: ElevatedButton.icon(
+                        onPressed: onCenterButtonPressed,
+                        icon: const Icon(Icons.edit_rounded, size: 18),
+                        label: const Text('写日记'),
+                        style: ElevatedButton.styleFrom(
+                          backgroundColor: AppColors.accent,
+                          foregroundColor: const Color(0xFFFFF8F0),
+                          shape: RoundedRectangleBorder(
+                            borderRadius: AppRadius.pillBorder,
+                          ),
+                        ),
+                      ),
                     ),
-                  ),
                 ],
               ),
             ),